Method Of Manufacturing Silicone Hydrogel Contact Lenses Having Reduced Rates Of Evaporation

ABSTRACT

A wettable silicone hydrogel contact lens having a low ionoflux and low evaporation is manufactured by curing a silicone hydrogel polymerizable composition in a contact lens mold comprising front and back lens-forming surfaces, where one of the lens-forming surfaces has a higher polarity than the other lens-forming surface.

This application claims the benefit under 35 U.S.C. §119(e) of priorU.S. Provisional Patent Application No. 62/362,283, filed Jul. 14, 2016,which is incorporated in its entirety by reference herein.

FIELD

The field of the invention relates to silicone hydrogel contact lenses.

BACKGROUND

Silicone hydrogel contact lenses are typically made by co-polymerizingone or more silicone-containing monomers with one or morehydrophilic-containing monomers within a contact lens mold that shapesthe front and back surfaces of the contact lens. After polymerization,the lens is removed from the mold and processed to hydrate and removeunreactive materials from the lens. Lenses may be subjected to furtherprocesses to increase the hydrophilicity of the surface of the contactlens. Typically the front (i.e. anterior) and back (i.e. posterior)surfaces of a contact lens have the same material properties. However,the two surfaces are exposed to very different environments. The frontsurface of a lens is exposed to the air-tear interface, where water fromwithin the hydrogel lens is susceptible to evaporation. The back surfaceof the lens is exposed to the eye-cornea interface. It has been proposedthat contact lens dehydration is induced by water evaporation at theanterior surface followed by water transport from the posterior to theanterior lens surface (see Little and Bruce, ICLC 22 (1995) 148-155),which can lead to thinning of post-lens tear film and in turn may leadto corneal epithelial cell damage, as evidenced by a fluorescein eyestain test. Contact lens discomfort is commonly associated with cornealstaining.

New silicone hydrogel contact lenses that are less susceptible todehydration, have reduced incidence of corneal staining, and are morecomfortable for the wearer are desired.

Background publications include U.S. Pat. No. 6,551,531, U.S. Pat. No.8,979,261, U.S. Publ. No. 2016/0159019, U.S. Publ. No. 2008/02950534,and U.S. Pat. No. 9,156,214.

SUMMARY

In one aspect, the invention provides a method of manufacturing asilicone hydrogel contact lens comprising providing a contact lens moldcomprising a first lens-forming surface to mold one side of saidhydrogel contact lens and a second lens-forming surface to mold theopposite side of said hydrogel contact lens, wherein the firstlens-forming surface has a higher polarity than the second lens-formingsurface; curing a polymerizable composition comprising at least onesiloxane monomer and at least one hydrophilic monomer in the contactlens mold to form a polymeric lens body; hydrating the polymeric lensbody to provide a silicone hydrogel contact lens having a first surfaceformed by the first lens-forming surface of the contact lens mold and asecond surface formed by the second lens-forming surface of the contactlens mold; and sealing the silicone hydrogel contact lens in a package.In one example, the silicone hydrogel contact lens manufactured by themethod has a lower ionoflux and/or a lower evaporation rate than acontrol contact lens manufactured by an identical method except that thesecond lens-forming surface has the same polarity as the firstlens-forming surface.

In another aspect, the invention provides a silicone hydrogel contactlens comprising a polymeric lens body that is the reaction product of apolymerizable composition comprising at least one siloxane monomer andat least one hydrophilic monomer, wherein the silicone hydrogel contactlens has an ionoflux between 1.0×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min and aback surface contact angle of less than 45°.

In another aspect, the invention provides a silicone hydrogel contactlens comprising a polymeric lens body that is the reaction product of apolymerizable composition comprising at least one siloxane monomer andat least one hydrophilic monomer, wherein the silicone hydrogel contactlens has an ionoflux between 1.0×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min andan evaporation rate of less than 15 mg/h when measured at 21° C. to 23°C. at 48-50% RH for 2 to 4 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a device used to measure ionoflux of a silicone hydrogelcontact lens.

DETAILED DESCRIPTION

Methods are described for manufacturing silicone hydrogel contact lensesthat have low ionoflux and/or reduced evaporation rates. The methodcomprises curing a polymerizable composition comprising at least onesiloxane monomer and at least one hydrophilic monomer in a contact lensmold comprising two lens-forming surfaces, where one lens-formingsurface, referred to herein as “the first lens-forming surface”, is morepolar than the complementary (i.e. the second) lens-forming surface. Theresulting silicone hydrogel contact lens has a lower ionoflux and/orreduced evaporation rate than a lens manufactured by the same methodexcept that both lens-forming surfaces of the contact lens mold comprisethe same “more polar” surface. The resulting lens is referred to hereinas a “dual-surface lens” because the difference in polarity between thefirst and second lens-forming surfaces of the contact lens mold resultsin a contact lens having front and back surfaces with different physicalproperties.

Contact lens molds typically comprise two combinable parts, one part isreferred to as the female mold member, which has a concave surface thatdefines the front (i.e. anterior) surface of the contact lens, and theother part is referred to as the male mold member, which has a convexsurface that defines the back (i.e. posterior) surface of the contactlens. A polymerizable composition is dispensed into the female moldmember and the male mold member is coupled to the female mold member toform a mold assembly having a lens-shaped cavity with the polymerizablecomposition therebetween. The mold assembly is then subjected toconditions that result in polymerization of the polymerizablecomposition.

The contact lens mold may be formed from any suitable material providedthat the mold has a first lens-forming surface that is more polar thanthe second lens-forming surface. In one example, the first lens-formingsurface has a percent polarity that is at least 3, 5, 10 or 15percentage points higher than the percent polarity of the secondlens-forming surface, and up to about 25, 30, 40, or 50 percentagepoints higher, where percent polarity of a molding material isdetermined by the Owens, Wendt, Rabel and Kaelble (OWRK) method. In oneexample, the first lens-forming surface of the contact lens mold formsthe front surface of the contact lens. In another example, the firstlens-forming surface of the contact lens mold forms the back surface ofthe contact lens. A first lens-forming surface of a contact lens mold isconsidered to be more polar than a second lens-forming surface of thecontact lens mold if the first lens-forming surface has a lower contactangle than the second lens-forming surface. As used herein, the contactangle of a lens-forming surface of a contact lens mold is determined bythe sessile drop method using a DSA-100 Drop Shape Analysis System fromKrüss, or equivalent analyzer, using 3 μl PBS dropped at the center ofthe lens-forming surface. In one example the contact angle of the firstlens-forming surface is at least 10°, 20°, or 30° lower than the contactangle of the second lens-forming surface. In another example, the firstlens-forming surface is polar and the second lens-forming surface isnon-polar. A lens-forming surface having a contact angle of 90° or lessindicates a polar surface, and a lens-forming surface having a contactangle of greater than 90° indicates a non-polar surface. Throughout thisdisclosure, a reference to “an example” or “a specific example” orsimilar phrase, is intended to introduce a feature or features of thecontact lens mold, polymerizable composition, method of manufacture,etc. (depending on context) that can be combined with any combination ofpreviously-described or subsequently-described examples (i.e. features),unless a particular combination of features is mutually exclusive, or ifcontext indicates otherwise.

In one example, the contact lens mold members are formed from athermoplastic polymer. Each of the mold members may be formed from thesame material or a different material. In examples where the moldmembers are formed from the same material, the lens-forming surface ofone of the mold members may be coated or treated to provide a differentsurface polarity than the lens-forming surface of the other mold member.In one example, both mold members comprise a non-polar material.Examples of non-polar materials suitable for contact lens molds includepolypropylene, cyclic olefinic polymers and copolymers, polyethylene,polystyrene, nylon polymers, and the like. In examples where both moldmembers comprise the same non-polar material, the first lens-formingsurface of the contact lens mold may be treated to make the surface morepolar than the second lens-forming surface. In one example the firstlens-forming surface may be made more polar by treatment with airplasma, UV-ozone, or corona discharge. In another example, the firstlens-forming surface may be coated with a hydrophilic coating. In aspecific example, the first lens-forming surface comprises a non-polarthermoplastic material coated with a hydrophilic coating and the secondlens-forming surface comprises the non-polar thermoplastic free of apolarity-enhancing surface coating or treatment.

A hydrophilic coating may comprise a hydrophilic polymer. Examples ofhydrophilic polymers include polyvinyl alcohol (PVOH) homopolymers, PVOHcopolymers, ethylene vinyl alcohol copolymers, polyethylene oxides,polyethylene oxide copolymers, polypropylene glycol, polyvinylpyrrolidone, carboxymethyl cellulose, hydroxypropyl methyl cellulose,polyacrylic acid, chitosan, hyaluronic acid, and combinations thereof. Ahydrophilic coating may be applied to the first lens-forming surface byany suitable coating method such spray coating, spin coating, dipcoating, roll coating, curtain coating, chemical vapor deposition, andcombinations thereof. Methods for applying hydrophilic coatings ontocontact lens molds are described in U.S. Publ. No. 2016/0159019, whichis incorporated herein by reference.

In some examples the second mold member is formed from a non-polarmaterial, such as one of the above non-polar thermoplastic polymers, andthe first mold member is made from a polar material. Examples of polarmaterials suitable for contact lens molds includes ethylene vinylalcohol copolymers, polyamide, polyvinyl alcohol resins having a1,2-diol structural unit, Nylon 6/6, Nylon 4/6, acetal resin, andpolybutylene terephthalate. Additional polar mold materials suitable forcontact lens molds are described in U.S. Pat. No. 8,979,261, and U.S.Pat. No. 9,156,214. In other examples, both mold members are formed froma polar material and the second lens-forming surface is treated to makethe surface less polar than the first lens-forming surface. For example,the second lens-forming surface may be coated with a hydrophobiccoating.

A polymerizable composition comprising at least one siloxane monomer andat least one hydrophilic monomer is dispensed into the contact lens moldand cured. The polymerizable composition, contact lens mold, and curingconditions are selected to provide a silicone hydrogel contact lens thathas a lower ionoflux and/or a reduced evaporation rate compared to acontrol contact lens. As used herein, the term “control contact lens”refers to a contact lens made from the same polymerizable composition asthe dual surface lens and manufactured by an identical method exceptthat the second lens-forming surface of the contact lens mold for thecontrol contact lens has the same polarity as the first lens-formingsurface. For example, if a contact lens of the present invention ismanufactured by curing a polymerizable composition in a polypropylenemold that has a PVOH coating on the first lens-forming surface and nocoating on the second lens-forming surface (i.e. the second lens-formingsurface is uncoated polypropylene), the same polymerizable compositionwhen cured in a polypropylene mold having the PVOH coating on both thefirst and second lens-forming surfaces of the polypropylene contact lensmold will result in a control contact lens having a higher ionofluxand/or evaporation rate.

As used herein, the term “ionoflux” refers to the ionoflux diffusioncoefficient value of a contact lens as determined by the methoddescribed in Example 1 below. In some examples, the ionoflux of thecontact lens is at least 1.0×10⁻⁶ mm²/min, 2.5×10⁻⁶ mm²/min, or 5.0×10⁻⁶mm²/min, and up to about 0.1×10⁻³ mm²/min, 0.25×10⁻³ mm²/min, 0.5×10⁻³mm²/min, 0.75×10⁻³ mm²/min, or 1.0×10⁻³ mm²/min. In one example, thecontact lens has an ionoflux of at least 1.0×10⁻⁶ mm²/min and up to0.5×10⁻³ mm²/min, and the control contact lens has an ionoflux ofgreater than 1.0×10⁻³ mm²/min or greater than 2.0×10⁻³ mm²/min. Thus, inthis example, the ionoflux of the control lens is more than twice thatof the dual-surface lens.

The “evaporation rate”, as used herein, refers to the average rate ofevaporation in units of mg/hr through the contact lens for a given timeperiod (e.g. 0 to 2 hours, 0 to 4 hours, 2 to 4 hours, etc.) as measuredin vitro using the method described in Example 2 below. In one example,the contact lens has an evaporation rate of less than 20 mg/h, less than18 mg/h, or less than 15 mg/h when measured at 21° C. to 23° C. at38-40% RH from 0 to 4 hours. In another example, the contact lens has anevaporation rate of less than 15 mg/h or less than 12 mg/h when measuredat 21° C. to 23° C. at 49-50% RH from 2 to 4 hours. In one example thecontact lens has an evaporation rate that is no more than 90%, 85%, 80%,75%, 70%, or 65% that of a control lens when measured at 21° C. to 23°C. at 38-40% RH for 0 to 4 hours.

The polymerizable composition comprises a siloxane monomer, which is amolecule containing at least one siloxane (Si—O—Si) group and at leastone polymerizable group. In some examples the siloxane monomer maycomprise two or more polymerizable groups, and thus has cross-linkingfunctionality. Siloxane monomers useful in contact lens compositions arewell-known in the art (see, e.g., U.S. Pat. No. 8,658,747, U.S. Pat. No.6,867,245, U.S. Pat. No. 7,750,079, U.S. Pat. No. 7,572,841, U.S. Pat.No. 8,614,261, U.S. Pat. No. 8,129,442, and U.S. Pat. No. 8,865,789). Inspecific examples, the siloxane monomer comprises an acryl group. Asused herein, a monomer comprising an “acryl group” has the structure ofstructure (1):

where X is hydrogen or a methyl group; Z is oxygen, sulfur, or nitrogen;and R is the remainder of the monomer. In one example, all siloxanemonomers in the polymerizable composition comprise one or two acrylgroups, and no other polymerizable group. In a further example, thepolymerizable composition comprises a total amount of siloxane monomerof at least 20 wt. %, 30 wt. %, or 40 wt. % up to about 50 wt. %, 60 wt.% or 70 wt. %. As used herein, a given weight percentage (wt. %) isrelative to the total weight of all polymerizable ingredients in thepolymerizable composition; the weight of the polymerizable compositioncontributed by non-reactive components such as diluents is not includedin the wt. % calculation. Throughout this disclosure, when a series oflower limit ranges and a series of upper limit ranges are provided, allcombinations of the provided ranges are contemplated as if eachcombination were specifically listed. For example, in the above listingof weight percentages, all nine possible ranges of weight percentagesare contemplated (i.e. 20 wt. % to 50 wt. %, 20 wt. % to 60 wt. % . . .40 wt. % to 60 wt. %, and 40 wt. % to 70 wt. %). Further, throughoutthis disclosure, when a series of values is presented with a qualifierpreceding the first value, the qualifier is intended to implicitlyprecede each value in the series unless context dictates otherwise. Forexample, for the weight percentages listed above, it is intended thatthe qualifier “at least” implicitly precedes each of the values 30 and40, and the qualifier “to about” implicitly precedes each of 60 and 70.

The polymerizable composition also comprises a hydrophilic monomer,which is a water-soluble molecule that does not contain any siloxanegroups and comprises a single polymerizable group. By comparison, ahydrophilic molecule containing two or more polymerizable groups and nosiloxane group is referred to herein as a “cross-linking agent”, asdescribed further below. In a specific example, the hydrophilic monomeris a hydrophilic vinyl-containing monomer, which, as used herein, is anysiloxane-free hydrophilic monomer having a single polymerizablecarbon-carbon double bond (i.e., a vinyl group) present in its molecularstructure that is not part of an acryl group (as defined by structure1), where the carbon-carbon double bond of the vinyl group is lessreactive than the carbon-carbon double bond present in a polymerizablemethacrylate group (i.e. a group of structure 1 where X is a methylgroup and R is oxygen) under free radical polymerization. Thus, while acarbon-carbon double bond is present in a monomer comprising apolymerizable methacrylate group, as used herein such monomers are notconsidered to be vinyl monomers. Examples of hydrophilicvinyl-containing monomers that can be used in the polymerizablecomposition include hydrophilic monomers having a single vinyl ether, orvinyl ester, or allyl ester, or vinyl amide polymerizable group.Exemplary hydrophilic vinyl-containing monomers includeN-vinylacetamide, N-vinyl-N-methylacetamide (VMA),N-vinyl-N-ethylacetamide, N-vinyl-2-pyrrolidone (NVP), N-vinylformamide,N-vinyl-N-ethylformamide, N-vinyl isopropylamide, N-vinylcaprolactam,N-vinyloxycarbonyl-L-alanine, 1,4-butanediol vinyl ether (BVE), ethyleneglycol vinyl ether (EGVE), diethylene glycol vinyl ether (DEGVE), apoly(ethylene glycol) vinyl ether, or any combination thereof.

In one example, the polymerizable composition comprises at least 10 wt.%, 15 wt. %, 20 wt. %, or 25 wt. % up to about 45 wt. %, 60 wt. %, or 75wt. % of a hydrophilic vinyl monomer. In a specific example, thepolymerizable composition comprises about 30 wt. % to 40 wt. % of ahydrophilic vinyl monomer. In a further example, the polymerizablecomposition comprises about 30 wt. % to 40 wt. % of a hydrophilic vinylmonomer and about 40 wt. % to 60 wt. % of a siloxane monomer. As usedherein, a given weight percentage of a particular class of component(e.g., hydrophilic vinyl monomer, siloxane monomer, or the like) in thepolymerizable composition equals the sum of the wt. % of each ingredientin the composition that falls within the class. Thus, for example, apolymerizable composition that comprises 10 wt. % VMA and 25 wt. % NVPand no other hydrophilic vinyl monomer, is said to comprise 35 wt. %hydrophilic vinyl monomer. In one example, the polymerizable compositioncomprises NVP in amounts of at least 10 wt. %, 15 wt. %, or 20 wt. %,and up to about 30 wt. %, 40 wt. %, or 50 wt. %. In a further example,the polymerizable composition comprises about 15 wt. % to about 40 wt. %NVP and about 5 wt. % to about 20 wt. % VMA.

The polymerizable composition may comprise a hydrophilic acryl monomer.As used herein, a “hydrophilic acryl monomer” is any hydrophilicsiloxane-free monomer comprising a single acryl group of Structure 1,and no other polymerizable group. Exemplary hydrophilic acryl monomersinclude N,N-dimethylacrylamide, 2-hydroxyethyl methacrylate, ethoxyethylmethacrylamide, ethylene glycol methyl ether methacrylate, methylmethacrylate, 2-hydroxybutyl methacrylate, tert butyl methacrylate,isobornyl methacrylate, and combinations thereof. In one example, thepolymerizable composition comprises from about 1 wt. % or 5 wt. % up toabout 10 wt. %, 15 wt. %, 20 wt. %, or 25 wt. % of a hydrophilic acrylmonomer. In another example, the polymerizable composition comprises ahydrophilic vinyl monomer and a hydrophilic acryl monomer at a weightratio of at least 2 to 1, respectively.

The polymerizable composition may additionally comprise at least onecross-linking agent, which, as used herein, is a molecule having atleast two polymerizable groups and no siloxane groups. The cross-linkingagent may comprise acryl groups or vinyl groups, or both an acryl groupand a vinyl group. A variety of cross-linking agents suitable for use insilicone hydrogel polymerizable compositions are known in the field(see, e.g., U.S. Pat. No. 8,231,218, incorporated herein by reference).Examples of cross-linking agents that can be used in the polymerizablecompositions disclosed herein, include, without limitation, loweralkylene glycol di(meth)acrylates such as triethylene glycoldimethacrylate and diethylene glycol dimethacrylate; poly(loweralkylene) glycol di(meth)acrylates; lower alkylene di(meth)acrylates;divinyl ethers such as triethyleneglycol divinyl ether, diethyleneglycoldivinyl ether, 1,4-butanediol divinyl ether and1,4-cyclohexanedimethanol divinyl ether; divinyl sulfone; di- andtrivinylbenzene; trimethylolpropane tri(meth)acrylate; pentaerythritoltetra(meth)acrylate; bisphenol A di(meth)acrylate;methylenebis(meth)acrylamide; triallyl phthalate;1,3-Bis(3-methacryloxypropyl)tetramethyldisiloxane; diallyl phthalate;triallyl isocyanurate; and combinations thereof.

As will be appreciated by those skilled in the art, the polymerizablecomposition may comprise additional polymerizable or non-polymerizableingredients conventionally used in contact lens formulations such as oneor more of a polymerization initiator, a UV absorbing agent, a tintingagent, a dye, an oxygen scavenger, a chain transfer agent, a diluent, orthe like. In some examples, the polymerizable composition may include anorganic diluent to minimize phase separation between the hydrophilic andhydrophobic components of the polymerizable composition. Diluentscommonly used in contact lens formulations to reduce phase separationinclude hexanol, ethanol, and/or other alcohols. In other examples, thepolymerizable composition is substantially free of an organic diluent.In such examples, the use of siloxane monomers containing hydrophilicmoieties such as polyethylene oxide groups, pendant hydroxyl groups, orother hydrophilic groups, can improve compatibility of the siloxanemonomer with the hydrophilic monomers of the polymerizable composition,making the addition of diluent unnecessary. Non-limiting examples ofthese and additional ingredients that may be included in thepolymerizable composition are provided in U.S. Pat. No. 8,231,218.

The polymerizable composition is dispensed into a contact lens moldcomprising a first lens-forming surface having a higher polarity thanthe second lens-forming surface, as described above, and cured (i.e.polymerized) using any suitable curing method. Typically, thepolymerizable composition is exposed to polymerizing amounts of heat orultraviolet light (UV). In the case of UV-curing, also referred to asphotopolymerization, the polymerizable composition typically comprises aphotoinitiator such as benzoin methyl ether, 1-hydroxycyclohexylphenylketone, DAROCUR, or IRGACUR (available from Ciba Specialty Chemicals).Photopolymerization methods for contact lenses are described in, e.g.,U.S. Pat. No. 5,760,100. In the case of heat-curing, also referred to asthermal curing, the polymerizable composition typically comprises athermal initiator. Exemplary thermal initiators include2,2′-azobis(2,4-dimethylpentanenitrile) (VAZO-52),2,2′-Azobis(2-methylpropanenitrile) (VAZO-64), and 1,1′-azobis(cyanocyclohexane) (VAZO-88). Thermal polymerization methods forcontact lenses are described in, e.g., U.S. Pat. No. 8,231,218 and U.S.Pat. No. 7,854,866, which are incorporated herein by reference.

After curing, the resulting polymeric lens body is removed from the mold(delensed) and washed to extract any unreacted or partially reactedingredients and to hydrate the lens. The washing step involvescontacting the polymeric lens body with one or more volumes of one ormore washing liquids. In some examples, a first volume of washing liquidis used to “wet” delens the lens from the mold. In other examples, thelens is “dry-delensed” from the mold using a mechanical method. In someexamples, the washing liquid used to wash and hydrate the lens maycomprise one or more volatile organic solvents (e.g., methanol, ethanol,chloroform, or the like). In other examples, the lens is washed andhydrated using only washing liquids that are free of volatile organicsolvents. Thus, in one example, the washing step is conducted in theabsence of liquids comprising volatile organic solvents.

After the curing step or washing step, the polymeric lens body may besubjected to a surface modification treatment to increase thewettability of the contact lens. In some examples, surface modificationmay be used to increase the wettability of the second surface of thecontact lens. In other examples, surface modification may be used toincrease wettability of both the first and second surfaces of thecontact lens. A variety of surface modification methods for increasingthe wettability of contact lens surfaces are known in the art. Examplesinclude plasma treatment, attachment of hydrophilic polymers onto thepolymeric lens body such as by a layer-by-layer technique, and additionof a hydrophilic polymer into the contact lens packaging solution. Theseand other methods of surface modification are known in the prior art(see e.g. U.S. Pat. No. 4,143,949, U.S. Pat. No. 7,582,327, and U.S.Pat. No. 7,841,716).

After washing, and any optional process step (e.g. surfacemodification), the hydrated polymeric lens body is placed into a blisterpackage, glass vial, or other appropriate container, all referred toherein as “packages.” Typically, packaging solution is also added to thecontainer. Suitable packaging solutions include phosphate- orborate-buffered saline together with any optional additional ingredientssuch as a comfort agent, a medication, a surfactant to prevent the lensfrom sticking to its package, or the like. The package is sealed, andthe sealed polymeric lens body is sterilized by radiation, heat or steam(e.g., autoclaving), gamma radiation, e-beam radiation, or the like. Insome examples, the lens may be packaged under sterile conditions, makinga post-packaging sterilization step unnecessary. In some examples, thepolymeric lens body may be dry delensed, placed directly into its finalpackage together with packaging solution, sealed, and optionallysterilized. Thus, the washing step may be concurrent with the packagingand sterilization steps. In a specific example, the polymeric lens bodyis sterilized by autoclaving.

Silicone hydrogel contact lenses manufactured by the methods describedherein have unique physical properties that increase their comfort andhelp maintain the corneal health of the patient. The silicone hydrogelcontact lens comprises a polymeric lens body that is the reactionproduct of a polymerizable composition comprising at least one siloxanemonomer and at least one hydrophilic monomer. The silicone hydrogelcontact lens comprises an optic zone that consists essentially of thereaction product of the polymerizable composition and any additionalchemicals or molecules added to the lens after polymerization, such asby post polymerization surface modification, contact with packagingsolution additives, etc. In other words, the silicone hydrogel contactlens comprises an optic zone that consists essentially of the siliconehydrogel. As used in this context, the term “consists essentially” meansthat the optic zone of the silicone hydrogel contact lens issubstantially free of non-silicone hydrogel components that affect theionoflux (i.e. that significantly reduce or increase the ionoflux) ofthe contact lens. Examples of non-silicone hydrogel components that mayaffect the ionoflux of a silicone hydrogel contact lens include variableoptic inserts, such as liquid crystal lenses or meniscus lenses. Anotherexample of a non-silicone hydrogel component is a non-silicone hydrogellayer of a composite or hybrid contact lens, such as a siliconeelastomer layer. In specific examples, the silicone hydrogel contactlens is characterized by having an ionoflux of at least 1.0×10⁻⁶mm²/min, 2.5×10⁻⁶ mm²/min, or 5.0×10⁻⁶ mm²/min and up to about 0.1×10⁻³mm²/min, 0.25×10⁻³ mm²/min, 0.5×10⁻³ mm²/min, 0.75×10⁻³ mm²/min, or1.0×10⁻³ mm²/min.

Another advantageous property of the silicone hydrogel contact lensesdescribed herein is that they have good wettability. In one example, thefront surface and/or the back surface of the contact lens has a contactangle that is less than 50°, 45°, 40°, 35°, 30°, or 25°. As used herein,the contact angle of a contact lens surface is the sessile drop contactangle of the back surface of the lens (unless the front surface isspecified) as measured by a DSA-100 Drop Shape Analysis System fromKrüss, or equivalent analyzer, using the method described in Example 3below. In a specific example, the silicone hydrogel contact lens has anionoflux between 1.0×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min and a sessiledrop contact angle of less than 45°. Curing the silicone hydrogelcontact lens in a mold with lens-forming surfaces having differentpolarities, as described above, may result in a contact lens havingfront and back surfaces with different wetting properties. In oneexample, the front surface of the silicone hydrogel contact lens has acontact angle that is at least 10%, 20%, 30%, or 40% greater than theback surface contact angle. In another example, the back surface of thecontact lens has a contact angle that is less than 30°.

In any of the above-described examples, the silicone hydrogel contactlens may have an evaporation rate of less than 20 mg/h, less than 18mg/h, or less than 15 mg/h when measured at 21° C. to 23° C. at 38-40%RH from 0 to 4 hours. In a specific example, the silicone hydrogelcontact lens has an evaporation rate of less than 15 mg/h when measuredat 21° C. to 23° C. at 38-40% RH from 0 to 4 hours, and an ionofluxbetween 0.25×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min. In another example, thecontact lens has an evaporation rate of less than 15 mg/h or less than12 mg/h when measured at 21° C. to 23° C. at 48-50% RH from 2 to 4hours, and an ionoflux between 0.25×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min.

In any of the above-described examples, the silicone hydrogel contactlens may have an equilibrium water content (EWC) of greater than about30 wt. %, 40 wt. % or 50 wt. % and up to about 60 wt. % or 70 wt. %. Tomeasure EWC, excess surface water is wiped off of the lens and the lensis weighed to obtain the hydrated weight. The lens is placed in an ovenat 80° C. under a vacuum until completely dried and weighed. The weightdifference is determined by subtracting the weight of the dry lens fromthe weight of the hydrated lens. The wt. % EWC of the lens is =(weightdifference/hydrated weight)×100.

In any of the above described examples, the silicone hydrogel contactlens may have a modulus of about 0.2 MPa, 0.3 MPa, or 0.4 MPa, up toabout 0.7 MPa, 0.8 MPa, or 0.9 MPa. As used herein, the modulus of acontact lens refers to the tensile modulus (i.e. Young's modulus) asmeasured using the method described in Example 4 below.

In any of the above-described examples, the silicone hydrogel contactlens may have an oxygen permeability (Dk) of at least 60, 80, or 100barrers. As used herein, the Dk of a contact lens is determined inaccordance with the American National Standards Institute (ANSI)Z80.20:2010, and International Organization for Standardization (ISO)18369-4:2006, in a humidity-saturated environment at 35° C. using anoxygen permeometer from Createch/Rehder Development Co. (West Lafayette,Ind.).

The following Examples illustrate certain aspects and advantages of thepresent invention, which should be understood not to be limited thereby.

Example 1: Ionoflux Method

Three 250 mL water jacketed reaction beakers are placed on magnetic stirplates and connected in series to a common circulating bath. Eachjacketed reaction beaker is filled with 80 mL deionized (DI) water andthe circulating bath is turned on to achieve a temperature of 35.5°±0.5°C. Three 100 ml beakers (receiving chambers) with magnetic stir bars arefilled with 80 mL water at about 40° C. and placed into each jacketedreaction beaker. Three calibrated conductivity meters (Horiba ModelES-51) and electrode cells (Horiba 3552-10D) are readied. Conductivityvalue at room temperature should be 1 μS/cm or less. A conductivityelectrode is immersed into each receiving chamber.

Each contact lens is rinsed by removing it from its original packagingsolution, placing it in a beaker with 30 mL of DI water at roomtemperature for 10 minutes, and placing it in 30 mL of fresh deonizedwater for an additional 10 minutes. The thickness of each rinsed lens ismeasured using a Rehder gauge Model ET-3 (West Lafayette, Ind.) at thefollowing five angles: 0, ±12°, ±16°, and the average thickness is takento be the thickness of the lens. Each lens is then placed in alens-retaining device of a donor chamber. Referring to FIG. 1, the donorchamber comprises a 30 ml clear glass vial, 1, with an open end, 2, anda threaded tapered end, 3, adapted to receive a threaded cap, 4. Thecenter of the cap has an 8.5 mm diameter circular opening. The rinsedcontact lens, 5, is mounted on a 14.2 mm diameter silicone O-ring, 6,having an 8.5 mm central opening (i.e. inner diameter), such that theperimeter of the back surface of the contact lens rests on top of theO-ring. If the diameter of the contact lens is greater than 14.2 mm itis trimmed with a 9/16 (˜14.2 mm) punch prior to placement on theO-ring. The O-ring is then placed on the threaded end of the donorchamber. The threaded cap, 4, is manually tightened onto the donorchamber until a torque of 1.9±0.1 N·cm is achieved to insure uniformityof tightness and adequate seal without damage to the lens. Torque isdetermined using a torque meter (IMADA DTX2-2B with 25 N·cm capacity and0.1 N·cm resolution). The donor chamber is turned upside down, asdepicted in FIG. 1, and filled with 5 mL DI water. The bottom (cappedend) of the donor chamber is wiped to check for water leaks. Ifnecessary, the lens and cap are re-assembled until no leakage isobserved. Once a leak-free seal is obtained the DI water is removed fromthe donor chamber and the donor chamber is placed into the receivingchamber, ensuring that no air bubbles are retained against the lens. 16mL of 0.1 M sodium chloride solution, 7, is added to the donor chamber.The level of the sodium chloride solution is adjusted to the same levelof the water inside the receiving chamber by moving the donor chamber upor down using a clamp. The electrode is adjusted using a clamp to ensurethat the ion junction is level with the lens assembly. Conductivity isrecorded for 20 minutes while the temperature inside the receivingchamber is 35.0±0.5° C.

Ionoflux is calculated for each lens by applying Fick's law of diffusionas follows: D=−n′/(A×dc/dx), where n′=rate of ion transport (mol/min),A=area of lens exposed (mm2), dc=concentration difference (mol/L), anddx=thickness of lens (mm), and D is the ionoflux diffusion coefficient,or simply “ionoflux”. The average ionoflux value of the three lenses istaken to be the ionoflux of the contact lens.

Example 2: Evaporation Rate Method

A threaded cap with the same configuration as described above for theionoflux method is used to secure a contact lens that has been rinsed asdescribed in Example 1. The cap is threaded onto a closed-ended 5 mlglass vial (as opposed to a 30 ml open-ended vial as described for theionoflux method) containing 1 ml PBS. As used herein, PBS refers to aphosphate buffered saline consisting of 0.83 wt. % NaCl, 0.03 wt. %sodium phosphate monobasic, and 0.24 wt. % sodium phosphate dibasichaving a pH of 7.3. The capped vial is checked for leaks as describedabove and reassembled if necessary to achieve a leak-free seal. Care istaken to ensure that the rinsed contact lens is promptly assembled withthe cap and vial so that it remains fully hydrated when the lens/vialassembly is first weighed. A rack for 5 ml glass vials is placed on ananalytical scale and the scale is tared to read zero. The capped vial isinverted (i.e. lens facing down) and carefully placed on the rack so asto ensure that the lens is not touched. Once placed in the rack, theweight of the capped vial is measured, and taken to be the weight attime=0 hours. The weight of the capped vial is measured again at times30, 60, 120 and 240 min, ensuring that the temperature is maintainedwithin a 2° C. range (e.g. 21° C. to 23° C.) and the relative humidityis maintained within a 2% range (e.g. 38-40% RH) during the duration ofthe testing. The evaporation rate for a given time range equals theweight at the beginning of the time period minus the weight at the endof the time period, divided by the time period. The average evaporationrate of the three lenses is taken to be the evaporation rate of thecontact lens. Thus, if a lens/vial set up has the following weights atthe time points shown in the table:

Time (min) Weight (mg) Difference from T₀ 0 1000  0 mg 30 990 10 mg 60985 15 mg 120 970 30 mg 240 960 40 mg

-   -   Then,    -   Evaporation rate from 0 to 2 hr=30 mg/2 hr=15 mg/hr    -   Evaporation rate from 2 to 4 hr=(40 mg-30 mg)/2 hr=5 mg/hr    -   Evaporation rate from 0 to 4 hr=40 mg/4 hr=10 mg/hr.

Example 3: Contact Angle Measurement

To determine the contact angle of a contact lens surface, contact lensesto be tested are soaked in PBS for at least 12 hours. Using rubbertipped tweezers, the lenses are removed from the PBS and shaken toremove excess water. A 4 mm diameter section of each lens is cut with alens cutter. The surface of the contact lens section to be tested isblotted dried by placing it face down on a microscope lens wipe andgently dragging the lens section across the wipe using rubber tippedtweezers until no liquid is observed absorbing into the wipe. The lenssection is placed on a microscope slide, ensuring that it lies flat withthe blotted surface facing upwards. Measurements are taken promptly toensure that the lens section does not become dry (as evidenced bydeformation of the lens section). The DSA-100, open the Drop ShapeAnalysis program is turned on and the “Sessile drop (VCA eq)” method isselected with the following settings: camera tilt=+2; Zoom=9; 100 μlsyringe with straight needle; dispense solution=purified water; dispensevolume=0.75 μl; dispense speed=7.5 μl/min; and dispense mode=volume. Themicroscope slide is placed on the sample stage so that the longer sideof the lens section is perpendicular to the camera. The syringe is movedto fit in the viewing screen and the image is adjusted until a maximumis reached in the median window. The water is dispensed onto the lens.Between 10 to 15 seconds after dispensing the water, the image of thedrop is captured. A calculation method is selected according to thecontact angle as follows: <30°=Circle Fitting Method, 30°-130°=TangentMethod−1; >130°=Tangent Method−2. The average contact angle measurementof 5 lens sections is taken to be the contact angle for the particularsurface (i.e. posterior or anterior) of the contact lens.

Example 4: Modulus Measurement

Young's modulus is determined by an ANSI Z80.20 standard using anInstron Model 3342 or Model 3343 mechanical testing system (InstronCorporation, Norwood, Mass., USA) and Bluehill Materials TestingSoftware. The contact lens to be tested is soaked in 4 mL phosphatebuffered saline (PBS) for 30 minutes prior to testing. While holding thelens concave side up, a central strip of the lens is cut using a contactlens cutting die having clean and sharp blades to provide a 4 mm widegenerally rectangular strip of the material that is defect-free alongthe cutting edges. The length of the strip is about 14-15 mm, that is,about the diameter of the contact lens before being cut. The thicknessof the strip is measured using a calibrated gauge (for example, Rehderelectronic thickness gauge, Rehder Development Company, Castro Valley,Calif., USA) at the following angles: −8°, −4°, 0°, 4°, and 8°. Theaverage of the 5 measurements is taken without correcting the values forcompression of the sample. Using tweezers, the strip is loaded into thegrips of the calibrated Instron apparatus, with the strip fitting overat least 75% of the grip surface of each grip; the gap distance betweenthe grips is 5.0 mm. The modulus is determined inside a humidity chamberhaving a relative humidity of at least 70% at room temperature (about22° C.) at a pull rate of 10.00 mm/min. The modulus is defined as thebeginning upward slope of the recorded curve.

Example 5: Preparation of Dual Surface Contact Lenses

A premix composition was prepared by combining the followingingredients: less than 1 wt. % sodium dioctyl sulfosuccinate, less than1 wt. % triallyl isocyanurate, about 53 wt. % N-vinyl-2-pyrrolidone,about 11 wt. % isobornyl methacrylate, about 18 wt. % 2-hydroxybutylmethacrylate, and about 18 wt. % N-vinyl-N-methylacetamide. Apolymerizable composition was prepared by combining about 51 wt. % ofthe premix composition with about 9 wt. % of a siloxane monomer having amolecular weight of about 1300, referred to as FMM (CAS #697234-76-7)and about 40 wt. % of a silicone macromer having a molecular weight ofabout 15000, referred to as M3U (CAS #697234-74-5). The structures ofthese siloxanes are provided in U.S. Pat. No. 7,750,079, incorporatedherein by reference.

The polymerizable composition was UV-cured in polypropylene contact lensmolds having a hydrophilic coating on the lens-forming surface of themale mold member. The female lens mold member was uncoated. The malemolds were coated by wetting their lens-forming surfaces with a solutionof 10% PVOH in water, spinning the male mold member for about 20 secondsat 8,800 RPM, and drying the male molds at room temperature between 1-24hours prior to use. After curing, the lenses were manually removed fromthe molds, hydrated in a hot (90° C.) bath of deionized water for 30minutes. The contact lenses were then extracted by soaking them in threeexchanges of industrial methylated spirits (IMS) containing about 95%ethanol and 5% methanol for 45 min each soak (i.e. approx. 135 min.total). The lenses were then soaked in three exchanges of 50% IMS+50% DIwater, and finally three exchanges of DI water. Control lenses were madeusing the same polymerizable composition and same method, except thatboth the male and female lens mold members were coated with the PVOH.

To increase the wettability of the front of the lens which was molded bythe uncoated polypropylene female mold member, some of the lenses weresoaked in two exchanges of a solution of 0.5% polyacrylic acid (PAA;ave. MW=250,000) in water with pH=2.0 for 20 minutes each soak, followedby soaking in two exchanges of PBS for 5 minutes each soak. The lenseswere then packaged in contact lens blisters containing PBS, sealed, andautoclaved.

The ionoflux and the evaporation rates of dual surface lenses with andwithout PAA treatment, as well as control lenses, were determined usingthe methods described above. The evaporation rates were tested using ahumidity chamber at 48-50% RH and temperature of 21° C. to 23° C., andevaporation rates from 2 to 4 hours were calculated. The results areshown in Table 1.

TABLE 1 Evaporation Rate Ionoflux Lens PAA Treated? (mg/hr) (mm²/min)Dual Surface Yes 10.0 ± 1.0 0.09 × 10⁻³ Dual Surface No 11.7 ± 2.5 0.12× 10⁻³ Control Yes 17.7 ± 1.0 4.17 × 10⁻³ Control No 17.8 ± 1.0 4.03 ×10⁻³

The disclosure herein refers to certain illustrated examples, it is tobe understood that these examples are presented by way of example andnot by way of limitation. The intent of the foregoing detaileddescription, although discussing exemplary examples, is to be construedto cover all modifications, alternatives, and equivalents of theexamples as may fall within the spirit and scope of the invention asdefined by the additional disclosure.

The present invention includes the followingaspects/embodiments/features in any order and/or in any combination:

-   1. A method of manufacturing a silicone hydrogel contact lens    comprising:    -   a. providing a contact lens mold comprising a first lens-forming        surface to mold one side of said hydrogel contact lens and a        second lens-forming surface to mold opposite side of said        hydrogel contact lens, wherein the first lens-forming surface        has a higher polarity than the second lens-forming surface;    -   b. curing a polymerizable composition comprising at least one        siloxane monomer and at least one hydrophilic monomer in the        contact lens mold to form a polymeric lens body;    -   c. hydrating the polymeric lens body to provide a silicone        hydrogel contact lens having a first surface formed by the first        lens-forming surface of the contact lens mold and a second        surface formed by the second lens-forming surface of the contact        lens mold; and    -   d. sealing the silicone hydrogel contact lens in a package,    -   wherein the silicone hydrogel contact lens has a lower ionoflux        and/or a lower evaporation rate than a control contact lens        manufactured by an identical method except that the second        lens-forming surface has the same polarity as the first        lens-forming surface.-   2. The method of any preceding or following    embodiment/feature/aspect, wherein the first lens-forming surface    has a contact angle that is at least 20° lower than the contact    angle of the second lens forming surface.-   3. The method of any preceding or following    embodiment/feature/aspect, wherein the first lens-forming surface is    polar and the second lens-forming surface is non-polar.-   4. The method of any preceding or following    embodiment/feature/aspect, wherein the first lens-forming surface    comprises a non-polar thermoplastic material coated with a    hydrophilic coating, and wherein the second lens-forming surface    comprises the non-polar thermoplastic material in the absence of any    polarity-enhancing surface coating or treatment.-   5. The method of any preceding or following    embodiment/feature/aspect, wherein the at least one hydrophilic    monomer is a hydrophilic vinyl-containing monomer.-   6. The method of any preceding or following    embodiment/feature/aspect, wherein the polymerizable composition    comprises a total amount of hydrophilic vinyl-containing monomer of    about 20 wt. % to about 60 wt. % based on the total weight of all    polymerizable ingredients in the polymerizable composition.-   7. The method of any preceding or following    embodiment/feature/aspect, where the at least one hydrophilic    vinyl-containing monomer is selected from N-vinylacetamide,    N-vinyl-N-methylacetamide (VMA), N-vinyl-N-ethylacetamide,    N-vinyl-2-pyrrolidone (NVP), N-vinylformamide,    N-vinyl-N-ethylformamide, N-vinyl isopropylamide,    N-vinylcaprolactam, N-vinyloxycarbonyl-L-alanine, 1,4-butanediol    vinyl ether, ethylene glycol vinyl ether, diethylene glycol vinyl    ether, a poly(ethylene glycol) vinyl ether, or any combination    thereof-   8. The method of any preceding or following    embodiment/feature/aspect, wherein the hydrophilic vinyl-containing    monomer is VMA, or NVP, or a combination of both VMA and NVP.-   9. The method of any preceding or following    embodiment/feature/aspect, wherein the polymerizable composition    comprises a total amount of siloxane monomer of about 30 wt. % to    about 60 wt. % based on the total weight of all polymerizable    ingredients in the polymerizable composition.-   10. The method of any preceding or following    embodiment/feature/aspect, wherein after the curing step the    polymeric lens body is subjected to a surface modification treatment    to increase wettability of the second surface of the silicone    hydrogel contact lens.-   11. The method of any preceding or following    embodiment/feature/aspect, wherein the surface modification    treatment is selected from air plasma, or UV-ozone, or corona    discharge.-   12. The method of any preceding or following    embodiment/feature/aspect, wherein the contact lens has an    equilibrium water content (EWC) of at least 40%.-   13. The method of any preceding or following    embodiment/feature/aspect, wherein the contact lens has an ionoflux    of less than 0.5×10⁻³ mm²/min, and the control contact lens has an    ionoflux of at least 1×10⁻³ mm²/min.-   14. The method of any preceding or following    embodiment/feature/aspect, wherein the contact lens has a lower    evaporation rate from 2 to 4 hours than the control lens, wherein    the evaporation rate measured at 48-50% RH and 21° C. to 23° C.-   15. The method of any preceding or following    embodiment/feature/aspect, wherein the evaporation rate is less than    15 mg/h.-   16. The method of any preceding or following    embodiment/feature/aspect, wherein the first surface of the contact    lens has a sessile drop contact angle that is less than that of the    second surface of the contact lens.-   17. The method of any preceding or following    embodiment/feature/aspect, wherein the contact lens has a back    surface having a contact angle of less than 45°.-   18. The method of any preceding or following    embodiment/feature/aspect, wherein the first surface of the contact    lens is a back surface.-   19. The method of any preceding or following    embodiment/feature/aspect, wherein the first surface of the contact    lens is a front surface.-   20. A silicone hydrogel contact lens comprising a polymeric lens    body that is the reaction product of a polymerizable composition    comprising at least one siloxane monomer and at least one    hydrophilic monomer, wherein the silicone hydrogel contact lens has    an ionoflux between 1.0×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min and a) a    back surface contact angle of less than 45°, or b) an evaporation    rate of less than 15 mg/h when measured at 21° C. to 23° C. at    48-50% RH for 2 to 4 hours, or 3) both a back surface contact angle    of less than 45° and an evaporation rate of less than 15 mg/h when    measured at 21° C. to 23° C. at 48-50% RH for 2 to 4 hours, wherein    the silicone hydrogel contact lens comprises an optic zone that    consists essentially of the silicone hydrogel.-   21. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, having a back surface contact angle of    less than 45°.-   22. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, wherein the back surface contact angle is    less than 30°.-   23. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, having an evaporation rate of less than    15 mg/h when measured at 24° C. at 49-50% RH for 2 to 4 hours.-   24. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, wherein the evaporation rate is less than    12 mg/h.-   25. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, wherein the ionoflux is less than    0.1×10⁻³ mm²/min.-   26. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, having a front surface contact angle that    is at least 10% greater than the back surface contact angle.-   27. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, wherein the at least one hydrophilic    monomer is a hydrophilic vinyl-containing monomer.-   28. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect, where the at least one hydrophilic    vinyl-containing monomer is selected from N-vinylacetamide,    N-vinyl-N-methylacetamide (VMA), N-vinyl-N-ethylacetamide,    N-vinyl-2-pyrrolidone (NVP), N-vinylformamide,    N-vinyl-N-ethylformamide, N-vinyl isopropylamide,    N-vinylcaprolactam, N-vinyloxycarbonyl-L-alanine, 1,4-butanediol    vinyl ether, ethylene glycol vinyl ether, diethylene glycol vinyl    ether, a poly(ethylene glycol) vinyl ether, or any combination    thereof.-   29. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect having an EWC of at least 30%.-   30. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect wherein the EWC is about 40% to about 60%.-   31. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect having a modulus about 0.3 MPa up to about    0.9 MPa.-   32. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect having a Dk of at least 80 barrers.-   33. The silicone hydrogel contact lens of any preceding or following    embodiment/feature/aspect that is sterile and sealed a package.

The entire contents of all cited references in this disclosure, to theextent that they are not inconsistent with the present disclosure, areincorporated herein by reference.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present invention disclosed herein. It is intended thatthe present specification and examples be considered as exemplary onlywith a true scope and spirit of the invention being indicated by thefollowing claims and equivalents thereof.

What is claimed is:
 1. A method of manufacturing a silicone hydrogelcontact lens comprising: a. providing a contact lens mold comprising afirst lens-forming surface to mold one side of said hydrogel contactlens and a second lens-forming surface to mold opposite side of saidhydrogel contact lens, wherein the first lens-forming surface has ahigher polarity than the second lens-forming surface; b. curing apolymerizable composition comprising at least one siloxane monomer andat least one hydrophilic monomer in the contact lens mold to form apolymeric lens body; c. hydrating the polymeric lens body to provide asilicone hydrogel contact lens having a first surface formed by thefirst lens-forming surface of the contact lens mold and a second surfaceformed by the second lens-forming surface of the contact lens mold; andd. sealing the silicone hydrogel contact lens in a package, wherein thesilicone hydrogel contact lens has a lower ionoflux and/or a lowerevaporation rate than a control contact lens manufactured by anidentical method except that the second lens-forming surface has thesame polarity as the first lens-forming surface.
 2. The method of claim1, wherein the first lens-forming surface has a contact angle that is atleast 20° lower than the contact angle of the second lens formingsurface.
 3. The method of claim 1, wherein the first lens-formingsurface is polar and the second lens-forming surface is non-polar. 4.The method of claim 1, wherein the first lens-forming surface comprisesa non-polar thermoplastic material coated with a hydrophilic coating,and wherein the second lens-forming surface comprises the non-polarthermoplastic material in the absence of any polarity-enhancing surfacecoating or treatment.
 5. The method of claim 1, wherein the at least onehydrophilic monomer is a hydrophilic vinyl-containing monomer.
 6. Themethod of claim 1, wherein the polymerizable composition comprises atotal amount of hydrophilic vinyl-containing monomer of about 20 wt. %to about 60 wt. % based on the total weight of all polymerizableingredients in the polymerizable composition.
 7. The method of claim 5,where the at least one hydrophilic vinyl-containing monomer is selectedfrom N-vinylacetamide, N-vinyl-N-methylacetamide (VMA),N-vinyl-N-ethylacetamide, N-vinyl-2-pyrrolidone (NVP), N-vinylformamide,N-vinyl-N-ethylformamide, N-vinyl isopropylamide, N-vinylcaprolactam,N-vinyloxycarbonyl-L-alanine, 1,4-butanediol vinyl ether, ethyleneglycol vinyl ether, diethylene glycol vinyl ether, a poly(ethyleneglycol) vinyl ether, or any combination thereof.
 8. The method of claim7, wherein the hydrophilic vinyl-containing monomer is VMA, or NVP, or acombination of both VMA and NVP.
 9. The method of claim 1, wherein thepolymerizable composition comprises a total amount of siloxane monomerof about 30 wt. % to about 60 wt. % based on the total weight of allpolymerizable ingredients in the polymerizable composition.
 10. Themethod of claim 1, wherein after the curing step the polymeric lens bodyis subjected to a surface modification treatment to increase wettabilityof the second surface of the silicone hydrogel contact lens.
 11. Themethod of claim 10, wherein the surface modification treatment isselected from air plasma, or UV-ozone, or corona discharge.
 12. Themethod of claim 1, wherein the contact lens has an equilibrium watercontent (EWC) of at least 40%.
 13. The method of claim 1, wherein thecontact lens has an ionoflux of less than 0.5×10⁻³ mm²/min, and thecontrol contact lens has an ionoflux of at least 1×10⁻³ mm²/min.
 14. Themethod of claim 1, wherein the contact lens has a lower evaporation ratefrom 2 to 4 hours than the control lens, wherein the evaporation ratemeasured at 48-50% RH and 21° C. to 23° C.
 15. The method of claim 14,wherein the evaporation rate is less than 15 mg/h.
 16. The method ofclaim 1, wherein the first surface of the contact lens has a sessiledrop contact angle that is less than that of the second surface of thecontact lens.
 17. The method of claim 1, wherein the contact lens has aback surface having a contact angle of less than 45°.
 18. The method ofclaim 1, wherein the first surface of the contact lens is a backsurface.
 19. The method of claim 1, wherein the first surface of thecontact lens is a front surface.
 20. A silicone hydrogel contact lenscomprising a polymeric lens body that is the reaction product of apolymerizable composition comprising at least one siloxane monomer andat least one hydrophilic monomer, wherein the silicone hydrogel contactlens has an ionoflux between 1.0×10⁻⁶ mm²/min and 0.5×10⁻³ mm²/min anda) a back surface contact angle of less than 45°, or b) an evaporationrate of less than 15 mg/h when measured at 21° C. to 23° C. at 48-50% RHfor 2 to 4 hours, or 3) both a back surface contact angle of less than45° and an evaporation rate of less than 15 mg/h when measured at 21° C.to 23° C. at 48-50% RH for 2 to 4 hours, wherein the silicone hydrogelcontact lens comprises an optic zone that consists essentially of thesilicone hydrogel.
 21. The silicone hydrogel contact lens of claim 20,having a back surface contact angle of less than 45°.
 22. The siliconehydrogel contact lens of claim 21, wherein the back surface contactangle is less than 30°.
 23. The silicone hydrogel contact lens of claim20, having an evaporation rate of less than 15 mg/h when measured at 24°C. at 49-50% RH for 2 to 4 hours.
 24. The silicone hydrogel contact lensof claim 23, wherein the evaporation rate is less than 12 mg/h.
 25. Thesilicone hydrogel contact lens of claim 20, wherein the ionoflux is lessthan 0.1×10⁻³ mm²/min.
 26. The silicone hydrogel contact lens of claim20, having a front surface contact angle that is at least 10% greaterthan the back surface contact angle.
 27. The silicone hydrogel contactlens of claim 20, wherein the at least one hydrophilic monomer is ahydrophilic vinyl-containing monomer.
 28. The silicone hydrogel contactlens of claim 27, where the at least one hydrophilic vinyl-containingmonomer is selected from N-vinylacetamide, N-vinyl-N-methylacetamide(VMA), N-vinyl-N-ethylacetamide, N-vinyl-2-pyrrolidone (NVP),N-vinylformamide, N-vinyl-N-ethylformamide, N-vinyl isopropylamide,N-vinylcaprolactam, N-vinyloxycarbonyl-L-alanine, 1,4-butanediol vinylether, ethylene glycol vinyl ether, diethylene glycol vinyl ether, apoly(ethylene glycol) vinyl ether, or any combination thereof.
 29. Thesilicone hydrogel contact lens of claim 20 having an EWC of at least30%.
 30. The silicone hydrogel contact lens of claim 29 wherein the EWCis about 40% to about 60%.
 31. The silicone hydrogel contact lens ofclaim 20 having a modulus about 0.3 MPa up to about 0.9 MPa.
 32. Thesilicone hydrogel contact lens of claim 20 having a Dk of at least 80barrers.
 33. The silicone hydrogel contact lens of claim 20 that issterile and sealed a package.